Scattering on a rectangular potential barrier in nodal-line Weyl semimetals

TL;DR

This paper studies how particles scatter on a rectangular barrier in nodal-line Weyl semimetals, revealing unique Klein tunneling phenomena and reflectionless transmission at specific angles due to anisotropic crystal structure.

Contribution

It demonstrates the occurrence of Klein tunneling and reflectionless transmission at specific angles in nodal-line Weyl semimetals, highlighting effects of anisotropy and geometrical resonances.

Findings

Klein tunneling occurs at certain incident angles, not just 90°

Reflectionless transmission at 'magic angles' determined by geometrical resonances

Wave functions can be superpositions of two plane waves with different momenta

Abstract

We investigate single-particle ballistic scattering on a rectangular barrier in the nodal-line Weyl semimetals. Since the system under study has a crystallographic anisotropy, the scattering properties are dependent on mutual orientation of the crystalline axis and the barrier. To account for the anisotropy, we examine two different barrier orientations. It is demonstrated that, for certain angles of incidence, the incoming particle passes through the barrier with probability of unity. This is a manifestation of the Klein tunneling, a familiar phenomenon in the context of graphene and semimetals with Weyl points. However, the Klein tunneling in the Weyl-ring systems is observed when the angle of incidence differs from 90$^\circ$, unlike the cases of graphene and Weyl-point semimetals. The reflectionless transmission also occurs for the so-called `magic angles'. The values of `the magic angles' are determined by geometrical resonances between the barrier width and the de Broglie length of the scattered particle. In addition, we show that under certain conditions the wave function of the transmitted and reflected particles may be a superposition of two plane waves with unequal momenta. Such a feature is a consequence of the non-trivial structure of the iso-energy surfaces of the nodal-line semimetals.